292 Annals of the Carnegie Museum. 



The ulno-radius is very long and slender. The two bones are well 

 coossified, leaving little or no indication of a suture between them. 

 The olecranon process of the ulna projects but little above the sigmoid 

 notch and is much compressed transversely, while antero-posteriorly 

 its diameter is considerable ; it is in every respect similar to that in 

 Oxydactylus except in the absence of the groove for the extensor 

 tendon on the anterior superior face of the process. The absence of 

 this groove is also characteristic of the recent camels. The articula- 

 tion of the sigmoid notch is divided by a prominent ridge which is 

 placed further over towards the ulnar border than in Oxydactylus, and 

 in this respect it is more nearly like the recent camels. The radial 

 border of the sigmoid notch is different from that in Oxydactylus and 

 the recent camels in having an interrupted area in the deepest part of 

 the notch. This sulcus is comparatively shallow and does not extend 

 to the median ridge, thus leaving the internal facet for the humerus 

 uninterrupted throughout to the upper extremity of the sigmoid notch 

 of the ulna, as in the latter genera. The head of the radius has a 

 large tubercle for muscular attachment on the ulnar face, which adds 

 considerably to the transverse diameter and furnishes characters quite 

 similar to those in Camelus bactria?ius. Immediately below the head 

 of the radius the shaft of the ulno-radius is rapidly contracted, so that 

 its diameters are nearly uniform throughout. Proximally the shaft is 

 strongly arched forward, while the distal two thirds have an almost 

 vertical position when articulated with the limb. The distal end has 

 a considerable transverse expansion. The three facets for the carpus 

 are divided in nearly the same proportion as in the camel and Lama 

 huanaco, i. e., the facet for the pyramidal is broad, while that for the 

 lunar is of comparatively small transverse diameter. In Oxydactylus 

 the lunar facet occupies a comparatively greater area, while that for 

 the pyramidal is the smallest of the three. The articulation as a whole 

 has not the oblique appearance seen in the latter genus. 



Carpus. — The carpus as a whole is rather high and its transverse 

 diameter is correspondingly small. The scaphoid has very nearly the 

 same relative proportions as in Lama huanaco and is consequently of 

 proportionately greater transverse diameter than in Oxydactylus. The 

 lunar is more compressed laterally than in the latter genus and ap- 

 proaches more closely to the condition of this bone found in the 

 recent forms. The pyramidal again compares more closely with the 

 same bone in recent forms than in Oxydactylus, though possessing 



